1. Field of the Invention
This invention relates generally to the field of conveying articles for rearranging, and in particular, to methods and apparatus for mixing articles stacked in homogeneous layers on respective pallets.
2. Description of Related Art
A method and apparatus for rearranging articles palletized according to sorts, to form new groups of specific sort composition, is known from U.S. Pat. No. 5,269,646. As taught and claimed therein, a system for handling articles of different types comprises: a plurality of depallitizing stations; means for removing a layer of articles from a pallet, said removing means associated with each of the plurality of depallitizing stations; a plurality of band conveying means, each of the plurality of conveying means comprising a plurality of conveying bands; a plurality of sort conveying means, each of the plurality of sort conveying means being parallel to one another; a plurality of sort stores, each of the plurality of sort stores being parallel to one another; at least one group-forming station; and, group conveying means for transporting articles from the sort conveying means to the at least one group-forming station; wherein each of the plurality of depallitizing stations has associated therewith one of said band conveying means, each band conveying means has associated therewith a subset of said plurality of sort conveying means, the band conveying means conveying an article removed from the pallet by the removing means to one of the plurality of sort conveying means in the associated subset, and each sort conveying means has associated therewith a sort store for temporarily holding articles. A corresponding method is also taught and claimed. A significant problem with the foregoing system can be appreciated from FIG. 1 or 2 thereof, and the text, namely that a separate path 20, 21, 22, etc., is required for each row of articles in the stacked layers, and that each separate path requires a separate vertical stacking rack. The vertical stacking rack must operate bidirectionally. The system is further characterized by a continuous conveying path, which at times, has parallel branches. The cost of having multiple palletizing stations and multiple stacking racks may be reasonable for the small lightweight articles contemplated, which in the example have a length of only 255 mm, but the cost for multiple stations capable of large and heavier articles is prohibitive. While the use of a single conveying path may seem to simplify the system, it actually places greater restraints on the relative operating speeds of the different work stations, complicating overall control. Moreover, the multiple parallel conveying paths are difficult to coordinate in timing and, together with the multiple palletizing stations and multiple stacking racks, use a lot of floor space.